1. Field of the Invention
The present invention relates to an image transmission apparatus which generates and transmits an image, a display apparatus which receives the image from the image transmission apparatus and displays the received image, and a method to be performed in these apparatuses.
2. Related Art
In JP-A 2002-304283 (KOKAI), there is described an example of a system in which an information processing apparatus (image transmission apparatus) and a display apparatus can be connected via multiple communication paths. When the information processing apparatus and the display apparatus are wiredly connected, the system according to JP-A 2002-304283 (KOKAI) transmits an image to be displayed on the display apparatus via the wired connection. When detecting that the wired connection has been cut, the system transmits the image to be displayed on the display apparatus via wireless connection.
Thereby, when using the display apparatus near the information processing apparatus, a user can work with a high graphic performance via wired connection. Furthermore, it is also possible to perform work using the display apparatus away from the information processing apparatus, and in this case, the display apparatus receives an image to be displayed from the information processing apparatus via wireless connection.
As a scheme for compressing and transmitting information to be displayed on the display apparatus, there is widely used a scheme in which a whole image as an image of one frame to be displayed on the display apparatus is transmitted first, and then an image of an area where change has been made is transmitted at predetermined time intervals (see JP-A 2004-86550 (KOKAI)).
When this scheme is applied to the system of JP-A 2002-304283 (KOKAI), the whole image to be displayed must be transmitted first immediately after switching to transmission via wireless communication, and a lot of time is required for the transmission when the usable band is narrow. Furthermore, since update of the displayed image starts after the whole image has been transmitted, a lot of time is required until the screen display is started.